/* 页眉定义 */
.header {
    background-color: #f1f1f1;
    padding: 5px;
    text-align: center;
}

/* 左右宽度布局 */
.column {
    float: left;
    padding: 5px;
}
.column.side {
    max-width: 240px;
    width: 25%;
}
.column.content {
    width: 75%;
    font-size: 18px;
}

/* 侧边导航栏 */
.side_nav{
    min-width: 160px;
    background-color: #f8f8f8;
    overflow: auto;
}

/* 导航栏一级标题 */
.nav_l1 {
    line-height: 50px;
    cursor: pointer;
    font-size: 20px;
    text-align: left;
}
.nav_l1:hover{
    background-color: #d0d0d0;
}
.nav_l1_text{
    white-space: nowrap;
    margin-left: 5%;
}

/* 导航栏二级标题box */
.nav_l1_box{
    cursor: pointer;
    display: none;
}

/* 二级导航 */
.nav_l2 {
    margin: 20px auto;
    font-size: 18px;
    text-align: left;
}
.nav_l2:hover {
    background-color: #c0c0c0;
}
.nav_l2_text {
    margin-left: 10%;
}

